The invention relates to a tensioning device for elongating a screw connection which is composed of a threaded bolt and of a threaded nut that is supported on a fixed substructure by way of traction to the free threaded end portion of the threaded bolt.
The invention furthermore relates to a method for tightening a screw connection which is composed of a threaded bolt and of a threaded nut, by means of a tensioning device which elongates the threaded bolt in the longitudinal direction.
Finally, the invention relates to a threaded nut which is suitable for use in such a method.
A bolt-tensioning device of this type and a method of this type are known from US 2011/0271798 A1 and US 2014/0245868 A1. In order for the threaded bolt of the screw assembly to be elongated in the longitudinal bolt direction, a replaceable bush which is provided for screwing to the threaded bolt by way of a thread is disposed in a cylinder housing of the tensioning device. The replaceable bush may be subjected to traction by way of a hydraulic mechanism, so as to elongate the threaded bolt in this way. In order for the replaceable bush to be screwed onto the threaded bolt, the tensioning device is placed from above onto the top of the threaded bolt and is rotated about its own axis, on account of which the replaceable bush is screwed onto the threaded end portion of the threaded bolt. Such screwing-on while rotating the tensioning device about its own axis is time consuming and in view of the weight of screw-tensioning devices of this type also tedious. However, placing the bolt-tensioning device from above onto the top of the screw assembly is indeed the ideal case. The fitter, however, is often confronted with a situation in which screw bolts have to be re-tightened from below, that is to say in an overhead situation. Handling a bolt-tensioning device as described in US 2011/0271798 A1 and US 2014/0245868 A1 is associated with significant issues, since upward screwing-in has to be performed taking into account the substantial weight of the bolt-tensioning device.
It is the object of the invention to provide a device which is particularly suitable for re-tightening a screw connection and which is also suitable for employment in other orientations and even in the case of overhead screw-assembly jobs. Furthermore, a respective method for tightening the screw connection, and a threaded nut which is suitable therefor are to be provided.